# Tables: Unnecessary duplication of id fields **URL:** \ **Category:** Ruby\ **Created:** [June 30, 2008, 6:12pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799 "2008-06-30T18:12:30Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [June 30, 2008, 6:12pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/1 "2008-06-30T18:12:30Z")
=begin Hello, I’m fairly new to Ruby, but I am trying to understand the relationship between database structure and models. My difficulty is that I have five or so tables all linked together and their primary key column is a serial number The tables are a set of tables called: itemmasters products prices subprices imprints etc. products, prices, and subprices, imprints, etc. belong to itemmasters based on a serial number How can I get about linking them without having to have a column in itemmasters for each of the sub tables? For instance: product\_id price\_id subprice\_id imprint\_id This would be somewhat silly as they all contain the same information. Right? Thank you, Brian A. =end ---
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [June 30, 2008, 6:33pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/2 "2008-06-30T18:33:00Z")
On Mon, Jun 30, 2008 at 11:09 AM, brian [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The tables are a set of tables called: > > This would be somewhat silly as they all contain the same information. > Right? > > Thank you, > > Brian A. > > =end While not really a Ruby or Rails question, it seems you have rows/tuples that point to a singular row in another table. In other words, reverse it. Have columns in your “subtables” that is the foreign key of the “master” one. It’s possible I misread your question, though. I do that pretty frequently 🙂 Todd ---
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [June 30, 2008, 7:14pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/3 "2008-06-30T19:14:07Z")
=begin Thank you for the response. Maybe it will be clearer if I will just begin with the symptom. I am getting an error saying “Couldn’t find Itemprice without an ID” This message comes up even despite the fact that this is my controller: class ItempriceController \< ApplicationController def show @itemprices = Itemprice.find(params[:ItemSerial]) end end I am not finding Itemprice by id according to the above, but still I get this error. In my view as a test I have the following: \<% @page\_title = “#{@itemprices.Price1}” %\> -Brian ----- Original Message ----- From: “Todd B.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) To: “ruby-talk ML” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Sent: Monday, June 30, 2008 11:29 AM Subject: Re: Tables: Unnecessary duplication of id fields > =end ---
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [June 30, 2008, 10:42pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/4 "2008-06-30T22:42:38Z")
On Mon, Jun 30, 2008 at 12:10 PM, brian [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > end > > I am not finding Itemprice by id according to the above, but still I get > this error. > > In my view as a test I have the following: > > \<% @page\_title = “#{@itemprices.Price1}” %\> > > -Brian Hmm. I’m no Rails expert, but maybe you should check the type/class of the object params[:ItemSerial]. Just a thought. Also, your database setup may be strange for Rails as I alluded to earlier. I’ve actually had this error a few times before, but can’t remember how I fixed it 😕 Todd ---
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [July 8, 2008, 5:03pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/5 "2008-07-08T17:03:42Z")
Thanks all for the response. I will have to play with it some more this week, and update with how it goes… ---
**Author:** ![zakifataya](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/c89c15/32.png) [@zakifataya](https://www.ruby-forum.com/u/zakifataya)\ **Post date:** [June 30, 2008, 11:13pm UTC](https://www.ruby-forum.com/t/tables-unnecessary-duplication-of-id-fields/141799/6 "2008-06-30T23:13:39Z")
On Mon, Jun 30, 2008 at 2:38 PM, Todd B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > end > > -Brian > > Hmm. I’m no Rails expert, but maybe you should check the type/class > of the object params[:ItemSerial]. Just a thought. Also, your > database setup may be strange for Rails as I alluded to earlier. I’ve > actually had this error a few times before, but can’t remember how I > fixed it 😕 > > Todd It sounds to me like Itemprice.find(params[:ItemSerial]) is returning nil for whatever reason. This is getting passed along and then rails is trying to retrieve the item from the database using nil for the id in your view. If you are doing a find with one argument rails assumes that argument evaluates to an id value. If you want to match on a field you would need something like find(:all, :conditions =\> [“serial = ?”, params[:ItemSerial]]) – “Hey brother Christian with your high and mighty errand, Your actions speak so loud, I can’t hear a word you’re saying.” -Greg Graffin (Bad Religion)